The present invention relates to a drive unit such as a wiper device.
Conventionally, direct drive wiper devices have been proposed as one type of drive units. A direct drive wiper device includes a motor main body, which is a drive source. The output shaft of the motor main body is directly fixed to a wiper. For example, refer to Japanese Laid-Open Patent Publication No. 59-120551. Another type of wiper device uses a four-bar linkage, in which, when the output shaft is rotated one rotation, the wiper is caused to reciprocate (swing) once within an angle range of 90 degrees or 110 degrees. For example, refer to Japanese Laid-Open Patent Publication No. 2008-35629. Compared to a direct drive wiper device, a wiper device using a four-bar linkage increases the torque that acts from the output shaft to the wiper (the four-bar linkage). Thus, it is possible to reduce the torque (the torque of the output shaft) that is generated by a drive source (a motor main body and a worm gear in the example of Japanese Laid-Open Patent Publication No. 59-120551) and is required for rotating the wiper with a predetermined torque.
However, in recent years, to facilitate installation of wiper devices to vehicles, the size of drive source in drive units have been desired to be reduced. Specifically, in a case where a drive source is a motor main body, the motor main body is desired to be reduced in size. In a case where a drive source includes a motor main body and a reduction gear, at least one of the motor main body and the reduction gear is desired to be reduced in size.